磁敏感加权成像及T_2*梯度回波序列在颅内静脉血栓形成中的应用

目的分析大脑静脉系统血栓形成(cerebral venous thrombosis,CVT)的临床及影像学特点,主要是磁敏感加权成像及T_2*梯度回波序列。方法收集我院11例大脑静脉系统血栓形成病例(6例皮质静脉血栓,4例静脉窦血栓,1例皮质静脉合并静脉窦血栓),分析其病因及影像学特点。结果 11例CVT女3例,男8例,平均年龄(40±21)岁。头部CT及MRI示不同脑叶出血性梗死、窦汇高密度、横窦束带征、静脉窦高信号等。MRV和全脑血管造影术(digital subtraction angiography,DSA)示静脉窦血栓形成,皮质静脉血栓或横窦乙状窦先天发育不良。头部MRI的SWI和T_2*序列示静脉窦血栓或皮质静脉区血栓,2例未发现异常。6例SWI和T_2*序列显示静脉血栓一致。2例SWI和T_2*序列阴性病例通过MRV或DSA诊断。结论 CVT是颅内静脉系统的血栓栓塞性疾病,多见于中青年,头部MRI的SWI像和T_2*序列对于皮质静脉血栓诊断非常重要,对于静脉窦血栓形成病例有很大帮助。T_2*和SWI序列可作为颅内静脉血栓形成的常规检查。     

Significance of the T2*-weighted gradient echo brain imaging in patients with infective endocarditis

Background

Although aneurysm formation accompanying parenchymal hemorrhage is one of devastating complications in the central nerves system (CNS), imaging studies of the brain are not routinely warranted in patients with infective endocarditis (IE). To assess the clinical importance for detecting silent lesions in the central nervous system, we investigated hypointense signal spots detected on the brain T2*-weighted MR imaging in patients with IE.

Methods and results

Eleven patients with IE were retrospectively reviewed. Seven patients (63.6%) showed hypointense signal spots on T2*-weighted MR images. The number of hypointense signal spots increased within only a few weeks in five patients.

Conclusion

The brain T2*-weighted MR imaging in patients with IE may have a potential role to detect CNS lesions with clinical significance of potentially high risk of intracranial hemorrhage. T2*-weighted hypointense signal spots may be specific to brain involvement, and be quite useful in monitoring CNS lesions associated with IE, even if they are asymptomatic.     

T2*-weighted MRI in diagnosis of multiple system atrophy

Abstract Background Putaminal iron deposition is a histopathological feature of multiple system atrophy (MSA), which is not observed in patients with idiopathic Parkinson's disease (PD). T2*-weighted magnetic resonance imaging (MRI) gradient echo (GE) sequences are sensitive for paramagnetic susceptibility changes and therefore may support the clinical differential diagnosis between MSA and PD. Methods We evaluated putaminal signal intensities on 1.0 Tesla scans of 52 MSA patients, 88 patients with PD and 29 healthy control subjects. Results The typical finding in T2* GE sequences of MSA patients was a signal loss of the dorsolateral putamen, which showed a high specificity (>0.91), but was present in only a subpopulation of patients (sensitivity 0.64–0.69). The combination of the latter with additional presence of a hyperintense lateral rim in fluid attenuated inversion recovery (FLAIR) sequences increased the specificity to 0.97. Using a quantitative evaluation of putaminal signal intensities in defined regions of interest MSA and PD could be discriminated with a diagnostic accuracy (r) of up to 0.82. Conclusion Although the separation of groups remains incomplete, the use of T2*-weighted GE sequences combined with FLAIR may be helpful for the differential diagnosis of MSA versus PD considering its fast application, easy evaluation, broad availability, the specificity of findings and the presence of putaminal signal loss already at early disease stages.     

T2-Weighted and T2 Relaxometry Images in Patients with Medial Temporal Lobe Epilepsy

PURPOSE: Quantification of increased T2-weighted MRI signal that is associated with hippocampal sclerosis (HS) can be performed through (1) mean of hippocampal signal in single-echo T2 MRI and (2) hippocampal T2 relaxometry. It is not clear whether these two techniques are equivalent. In this study, we compare the hippocampal signal, detected by single-echo T2 quantification and by T2 relaxometry, in patients with medial temporal lobe epilepsy (MTLE). METHODS: We studied magnetic resonance images from 50 MTLE patients and 15 healthy subjects. We compared the quantification of a T2 signal from single echo images to T2 relaxometry, both obtained from a manually traced region of interest (ROI) in coronal slices involving the whole hippocampus. Repeated measures ANOVA was used to evaluate the differences in the distribution of the Z-scores from single-echo T2 quantification and T2 relaxometry within subjects. RESULTS: We observed a significant difference between the measurements obtained from single-echo T2 quantification and T2 relaxometry (P < .001). Measurements from head, body, and tail of the hippocampus were different (P=.04), with a significant interaction between anatomic location and type of measurement used (P= .008). Post hoc paired comparisons revealed that T2 relaxometry yielded greater Z-scores for the body (P= .002) and tail (P < .0001). CONCLUSIONS: For each subject with MTLE, T2 relaxometry was able to detect a higher signal in the body and tail of the hippocampus compared to single-echo T2. This is a possible indicator that T2 relaxometry is more sensitive in detecting T2 abnormalities within the body and tail of the hippocampus in patients with MTLE.     

A meta-analysis showing that high signal intensity on T2-weighted MRI is associated with poor prognosis for patients with cervical spondylotic myelopathy

We used PubMed, Medline, and EMBASE to conduct a meta-analysis to determine the significance of high signal intensity on T2-weighted MRI for predicting postoperative prognosis in patients with cervical spondylotic myelopathy (CSM). Although patients with CSM with high signal intensity on T2-weighted MRI usually had a poor prognosis even after undergoing surgery, some researchers have argued recently that high-intensity signals are not associated with postoperative prognosis. Data consistent with the inclusion criteria of this study were cited for meta-analysis using Review Manager 5 Software. The postoperative recovery ratio specified by the Japanese Orthopedic Association (JOA) was assessed using the weighted mean difference (WMD) method. Five articles (one prospective; four retrospective) involving 309 patients with CSM were included. The aggregate WMD with regard to the postoperative JOA recovery ratio between the T2-weighted high signal intensity positive (+) group and the T2-weighted high signal intensity negative (-) group was -6.56, and the 95% confidence interval (CI) was -12.15 to -0.97 (p=0.02). Thus, we concluded that in patients with CSM, the postoperative JOA recovery ratio in the T2-weighted (+) group was lower than that in the T2-weighted (-) group.     

应用M模-TCD评价脑静脉及静脉窦血栓形成患者深静脉的动力学改变

目的 明确M模经颅多普勒检查（M模-TCD）在评估脑静脉及静脉窦血栓形成（cerebral vein andsinus thrombosis，CVT）患者大脑深静脉动力学改变中的价值。方法 应用M模-TCD（DWL Doppler Box，德国）对4例脑静脉系统血栓形成患者（观察组）及4例年龄及性别匹配的健康志愿者（对照组）的大脑中深静脉（dMCV）进行检测，记录dMCV的峰血流速度及脉动指数。结果 对照组中，dMCV的检出率为75％，平均峰血流速度为（14±2）cm/s；CVT患者中，dMCV的检出率为87.5％，4例患者均检测出一侧或两侧dMCV的峰血流速度的明显增加，平均峰血流速度为（55±25）cm/s。两组峰血流速度的差值具有统计学意义（P <0.01）。结论 对于CVT患者来说，M模-TCD可提供一种可靠、快速的检测深静脉动力学改变的非介入性技术。颅内深静脉血流速度的增加可能为CVT诊断的一个间接标准。     

Hematoma Size in Deep Intracerebral Hemorrhage and its Correlation with Dot-Like Hemosiderin Spots on Gradient Echo T2*-Weighted MRI

BACKGROUND AND PURPOSE: Dot-like low intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted MRI have been histologically diagnosed to represent old cerebral microbleeds associated with microangiopathies. They have also been correlated to the fragility of small vessels and the tendency to bleed. Therefore, a substantial number of dotHSs might be associated with a large-sized, deep intracerebral hematoma (ICH). On the other hand, dotHSs may reflect old microbleeds that did not enlarge to symptomatic size. METHODS: To investigate how dotHSs are related to the size (maximal diameter) of primary deep ICH, we analyzed the diameter and the number of dotHSs in 151 patients with deep ICH not associated with subarachnoid hemorrhage or intraventricular hemorrhage (75 males and 76 females, age ranged from 37 to 90 [65.7 +/- 11.3 years old] who were consecutively admitted to Hakodate Municipal Hospital. The hazard ratio (HR) for a maximal diameter of deep ICH < or =2 cm was estimated, using the number of dotHSs and risk factors for stroke. RESULTS: The number of dotHSs associated with the diameter < or =2 cm was 9.2 +/- 11.5, significantly larger than that with the diameter > or =2 cm (4.7 +/- 7.0, P= .012). Multivariate analysis revealed that a maximal diameter of deep ICH of < or =2 cm was found in patients with dotHS (HR, 3.7; 95% confidence interval [CI], 1.4-10.1; P= .009). CONCLUSION: Though small sample size limited the power of our analyses, these findings suggest that the number of dotHSs may be associated with a small diameter of deep ICH.     

磁共振成像T2*WI观察大鼠自发性脑出血含铁病灶的演变过程

目的:旨在研究用MRI T2*WI检测自发性脑出血后含铁病灶的演变过程.方法:大鼠脑内注射不同体积的自体动脉血(A组10μL;B组50μL;C组100μL).各组术后第1、3,7,14和30天行脑部MRI T2WI和T2*WI扫描,记录图像特征.由Image J软件进行图像分析.结果:大鼠脑内注射自体血后,MRI T2*WI图像较T2WI明显清晰;A、B组大鼠术后7和14 d含铁病灶体积T2*WI较T2WI所测得的体积更大(P<0.05); C组大鼠术后第7、14和30天,T2*WI比较T2WI测得的体积也更大(P<0.05).结论:在自发性脑出血后含铁病灶的检测中,MRI T2*WI较MRI T2WI更为清晰和敏感.     

2型糖尿病合并急性脑梗死hs-CRP、Lp(a)检测的临床价值

目的探讨2型糖尿病(DM)合并急性脑梗死(ACI)患者检测高敏C反应蛋白(hs-CRP)、脂蛋白a[Lp(a)]的临床价值。方法收集42例2型糖尿病合并急性脑梗死病例(DM+ACI组),40例单纯T2DM(DM组)及同期40例健康体检者(正常对照组),测定3组人群的hs-CRP、Lp(a)及其他生化指标,并对结果进行统计学分析。结果 DM+ACI组及DM组的血清hs-CRP、Lp(a)水平均显著高于正常对照组(P<0.05)。DM+ACI组血清Lp(a)显著高于DM组(P<0.05),2组hs-CRP水平比较差异无统计学意义(P>0.10)。结论 hs-CRP、Lp(a)检测对2型糖尿病并发急性脑梗死的风险度具有一定的预测价值。     

Altered T2* relaxation time of the hippocampus in major depressive disorder: Implications of ultra-high field magnetic resonance imaging

Previous studies with 1.5 T or 3.0 T magnetic resonance imaging (MRI) have produced mixed results regarding the structural changes of the hippocampus in major depressive disorder (MDD). Subtle region-specific hippocampal tissue changes might be more sensitively detected by measuring the T2* relaxation time (T2*-RT) by ultra-high-field (UHF) MRI, as it provides much higher contrast and sensitivity and consequently greater resolution. We assessed the T2*-RTs of hippocampal sub-regions in 16 MDD patients (9 with recurrent MDD) and 16 control subjects using an UHF 7.0 T MRI system. T2*-RTs of CA1, CA2, CA3, CA4, and subiculum were calculated for both left and right hippocampus. MDD patients had significantly longer T2*-RTs in the right CA1 and subiculum than control subjects. Patients with recurrent MDD had significantly longer T2*-RTs in the right subiculum than those experiencing a first depressive episode, and longer T2*-RTs in the right CA1, CA3, and subiculum than control subjects. Values for T2*-RTs of the right CA3 were significantly correlated with illness duration. In conclusion, we report that T2*-RTs in the right subiculum and CA1 were increased in patients with MDD, especially in cases of recurrent MDD. These findings suggest that region-specific hippocampal damage may be occurring in recurrent depression.     

Cerebral White Matter Maturation Patterns in Preterm Infants: An MRI T2 Relaxation Anisotropy and Diffusion Tensor Imaging Study

BACKGROUND AND PURPOSE

Preterm birth is associated with worse neurodevelopmental outcome, but brain maturation in preterm infants is poorly characterized with standard methods. We evaluated white matter (WM) of infant brains at term‐equivalent age, as a function of gestational age at birth, using multimodal magnetic resonance imaging (MRI).

METHODS

Infants born very preterm (<32 weeks gestation) and late preterm (33‐36 weeks gestation) were scanned at 3 T at term‐equivalent age using diffusion tensor imaging (DTI) and T2 relaxometry. MRI data were analyzed using tract‐based spatial statistics, and anisotropy of T2 relaxation was also determined. Principal component analysis and linear discriminant analysis were applied to seek the variables best distinguishing very preterm and late preterm groups.

RESULTS

Across widespread regions of WM, T2 is longer in very preterm infants than in late preterm ones. These effects are more prevalent in regions of WM that myelinate earlier and faster. Similar effects are obtained from DTI, showing that fractional anisotropy (FA) is lower and radial diffusivity higher in the very preterm group, with a bias toward earlier myelinating regions. Discriminant analysis shows high sensitivity and specificity of combined T2 relaxometry and DTI for the detection of a distinct WM development pathway in very preterm infants. T2 relaxation is anisotropic, depending on the angle between WM fiber and magnetic field, and this effect is modulated by FA.

CONCLUSIONS

Combined T2 relaxometry and DTI characterizes specific patterns of retarded WM maturation, at term equivalent age, in infants born very preterm relative to late preterm.     

A novel ferritin light chain gene mutation in a Japanese family with neuroferritinopathy: Description of clinical features and implications for genotype–phenotype correlations

Neuroferritinopathy is a hereditary neurodegenerative disorder caused by mutations in the ferritin light chain gene (FTL1). The cardinal features are progressive movement disturbance, hypoferritinemia, and iron deposition in the brain. To date, five mutations have been described in Caucasian and Japanese families, but the genotype–phenotype correlations remain to be established. We identified a novel FTL1 mutation (exon 4, c.641/642, 4‐nucletotide duplication) in a Japanese family and compared the clinical traits with those previously reported. All mutations but one are insertions in exon 4, resulting in frameshifts. Clinical features are similar among patients with the same mutations. Middle‐age onset chorea is common in patients with insertions in the 5′ portion of exon 4 including our cases, whereas patients with insertions in the 3′ portion of exon 4 develop early‐onset tremor, suggesting genotype–phenotype correlations. In this family, male predominance and normal serum ferritin levels are characteristic. © 2008 Movement Disorder Society     

Perfluorocarbons enhance a T2*-based MRI technique for identifying the penumbra in a rat model of acute ischemic stroke

Accurate imaging of ischemic penumbra is crucial for improving the management of acute stroke patients. T₂* magnetic resonance imaging (MRI) combined with a T₂*oxygen challenge (T₂*OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. Using 100% O₂, T₂*OC-defined penumbra exhibits ongoing glucose metabolism and tissue recovery on reperfusion. However, potential limitations in translating this technique include a sinus artefact in human scans with delivery of 100% OC and relatively small signal changes. Here we investigate whether an oxygen-carrying perfluorocarbon (PFC) emulsion can enhance the sensitivity of the technique, enabling penumbra detection with lower levels of inspired oxygen. Stroke was induced in male Sprague-Dawley rats (n=17) with ischemic injury and perfusion deficit determined by diffusion and perfusion MRI, respectively. T₂* signal change was measured in regions of interest (ROIs) located within ischemic core, T₂*OC-defined penumbra and equivalent contralateral areas during 40% O₂±prior PFC injection. Region of interest analyses between groups showed that PFC significantly enhanced the T₂* response to 40% O₂ in T₂*-defined penumbra (mean increase of 10.6±2.3% compared to 5.6±1.5% with 40% O₂, P<0.001). This enhancement was specific to the penumbra ROI. Perfluorocarbon emulsions therefore enhances the translational potential of the T₂*OC technique for identifying penumbra in acute stroke patients.     

MRI evaluation of the basal ganglia size and iron content in patients with Parkinson's disease

Objective To evaluate by MRI the area size and the degree of iron accumulation in basal ganglia nuclei that are implicated in the pathogenesis of Parkinson's disease (PD). Methods 40 patients with idiopathic PD and 40 controls were examined on a 1. 5 Tesla MR imager, using a multiecho SE sequence 2000/20, 40, 60, 80, 100, 120, 140, 160 (TR/TE). The T2 relaxation time (T2) and the area of substantia nigra zona compacta (SNc), substantia nigra zona reticulata (SNr), putamen (Pu), globus pallidus external (GPe), globus pallidus internal (GPi), caudate nucleus (CN), locus coeruleus (LC) and subthalamic nucleus (STN) were assessed. Results The T2 of SNc (76. 8 ± 6. 0) was lower and of Pu (79.5 ± 6.0) and GPe (69.5 ± 7.0) was higher in patients than in controls (78.6 ± 3.8, 77.4 ± 3.9 and 67.3 ± 5.7, respectively), p < 0.05. The area of CN (125.9 ± 20.2) and Pu (201.5 ± 48.7) was higher in patients than in controls (110.7 ± 21.5 and 180.1 ± 41.1, respectively), p < 0.05. A more pronounced decrease in the T2 of SNc (73.6 ± 8.9) was observed when the more affected side of patients was evaluated separately. In patients with disease duration > 5 years the T2 of STN (71.5 ± 6.3) was lower and the area of Pu was higher (215.3 ± 54.9) compared with those with disease duration ≤ 5 years (75.8 ± 10.9 and 190.9 ± 41.0 respectively), p < 0.05. Conclusions These findings suggest that dysfunction of the basal ganglia circuitry in PD may affect iron content not only in SNc but in STN, Pu and GPe as well. Compensatory sprouting of the remaining dopaminergic fibers could account for the increased area of the CN and Pu.     

Comparing diffusion-weighted and T2-weighted MR imaging for the quantification of infarct size in a neonatal rat hypoxic–ischemic model at 24 h post-injury

PURPOSE: In a neonatal rat model of hypoxic-ischemic (HI) brain injury, using T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI), we aim to determine the best MRI method of lesion quantification that reflects infarct size. MATERIALS AND METHODS: Twenty 7-day-old rats underwent MRI 24h after HI brain injury was induced. Lesion size relative to whole brain was measured using T2WI and apparent diffusion coefficient (ADC) maps, applying thresholds of 60%, 70% and 80% contralateral control hemisphere mean ADC, and at day 10 post-HI on pathology with TTC staining. Multiple linear regression analysis was used to study the relationships between lesion size at MRI and pathology. RESULTS: Lesion size measurement using all MRI methods significantly correlated with infarct size at pathology; using T2WI, r=0.808 (p<0.001), using 80% ADC, 70% ADC and 60% ADC thresholds, r=0.888 (p<0.001), 0.761, (p<0.001) and 0.569 (p=0.014), respectively. Eighty percent ADC threshold was found to be the only significant independent predictor of final infarct volume (adjusted R(2)=0.775). CONCLUSION: At 24h post-HI, lesion size on DWI, using 80% ADC threshold is the best predictor of final infarct volume. Although T2WI performed less well, it has the advantage of superior spatial resolution and is technically less demanding. These are important considerations for experiments which utilize MRI as a surrogate method for lesion quantification in the neonatal rat HI model.